#include <bits/stdc++.h>

using namespace std;

#define int long long

int32_t main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    vector a(n + 1, vector<array<int, 5>>(m + 1));
    string s;
    for (int i = 1; i <= n; i++) {
        cin >> s;
        for (int j = 1; j <= m; j++) {
            if (s[j - 1] == 'W') a[i][j][0]++;
            else if (s[j - 1] == 'A') a[i][j][1]++;
            else if (s[j - 1] == 'L') a[i][j][2]++;
            else if (s[j - 1] == 'D') a[i][j][3]++;
            else if (s[j - 1] == 'O') a[i][j][4]++;
        }
    }
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            for (int k = 0; k < 5; k++)
                a[i][j][k] += a[i - 1][j][k] + a[i][j - 1][k] - a[i - 1][j - 1][k];

    auto calc = [a, n, m](int r, int c, int x, int y) {
        for (int k = 0; k < 5; k++)
            if (a[x][y][k] - a[r - 1][y][k] - a[x][c - 1][k] + a[r - 1][c - 1][k] == 0) return false;
        return true;
    };
    int res = LLONG_MAX;
    for (int i = 1; i <= n; i++) {
        for (int j = 1, ans; j <= m; j++) {
            ans = LLONG_MAX;
            for (int l = i, r = n, p, f; l <= r;) {
                p = (l + r) >> 1, f = 0;
                for (int L = j, R = m, q; L <= R;) {
                    q = (L + R) >> 1;
                    if (calc(i, j, p, q)) ans = min(ans, (p - i + 1) * (q - j + 1)), f = 1, R = q - 1;
                    else L = q + 1;
                }
                if (f) res = min(res, ans), r = p - 1;
                else l = p + 1;
            }
        }
    }
    if( res == LLONG_MAX ) cout << "impossible\n";
    else cout << res << "\n";

    return 0;
}